OFFSET
0,2
LINKS
P. S. Bruckman and G. C. Greubel, Advanced Problem H-725, Fibonacci Quarterly, 52(2):187-190, 2014.
Index entries for linear recurrences with constant coefficients, signature (12,-48,64,-27).
FORMULA
a(n) = (9n + 7 + 3^(3n/2)*(11*sqrt(2)*cos(n*arcsin(sqrt(2/27))) + sin(n*arcsin(sqrt(2/27))))/sqrt(2))/18.
G.f.: (1-4x)^2/((1-4x)^3+27x^4) = (1-4*x)^2/((x-1)^2*(1 - 10*x + 27*x^2)).
MAPLE
Gser:=series((1-4*x)^2/((1-4*x)^3+27*x^4), x = 0, 35): seq(coeff(Gser, x, n), n = 0 .. 30);
MATHEMATICA
LinearRecurrence[{12, -48, 64, -27}, {1, 4, 16, 64}, 30] (* Harvey P. Dale, Nov 21 2015 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Emeric Deutsch, Oct 27 2014
STATUS
approved